1. Field of the Invention
The present invention relates to a semiconductor package having a semiconductor element and an interposer, and a printed circuit board having the semiconductor package and a printed wiring board.
2. Description of the Related Art
A semiconductor package has a semiconductor integrated circuit (LSI: Large-Scale Integration) which is a semiconductor element, and an interposer (package substrate) on which the LSI is mounted, and is operated by being mounted on a printed wiring board. A power supply circuit which supplies a direct current voltage necessary for the operation to the semiconductor package is mounted on the printed wiring board, and supplies the direct current voltage to the semiconductor package through the power line of the printed wiring board. An inductance component is contained in the power line, and when a current has passed through the power line, a power supply voltage occasionally fluctuates. In order to suppress the fluctuation of the power supply voltage which is supplied from this power supply circuit, it is common to provide a bypass capacitor between the power terminal and the ground terminal of the semiconductor package.
On the other hand, when the LSI is operated, a current due to the operation of the LSI passes sequentially through a power supplying route of the LSI, the package substrate, and the printed wiring board, the fluctuation of the power supply voltage occurs which is determined by a product of a power supply impedance that is parasitic characteristics of the power supplying route and the current that passes through the power supplying route. In a power supplying structure having the bypass capacitor, a capacitance component of the LSI and a parasitic inductance component that exists between the LSI and the bypass capacitor mounted on the printed wiring board form a parallel resonant circuit, which causes anti-resonance in a frequency band of the order of MHz and increases the power supply impedance. When the anti-resonance frequency has coincided with the operating frequency of the LSI, the power supply impedance of the anti-resonance frequency increases, and accordingly there are concerns that the large fluctuation of the power supply voltage occurs and causes the LSI to malfunction. Accordingly, in order to prevent the malfunction of the LSI, it is important to reduce an anti-resonance peak value of the power supply impedance of the MHz band.
Thus, Japanese Patent Application Laid-Open No. 2010-251373 describes a method of reducing the peak value of the anti-resonance of the power supply impedance, by mounting on the printed wiring board a capacitor which has a self-resonant frequency close to the anti-resonance frequency of the power supply impedance in the power supplying structure.
However, in the conventional example described in Japanese Patent Application Laid-Open No. 2010-251373, the capacitor element must be separately added in addition to the bypass capacitor in order to reduce the power supply impedance, and there has been a problem that the cost and the mounted area increase.